Does matlab create pointers to objects or create new copies?

Question

Evan Voyles 2020-5-29

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/536999-does-matlab-create-pointers-to-objects-or-create-new-copies

评论： Evan Voyles 2020-5-29

采纳的回答： per isakson

I'm building a simple grid simulation, where my class

contains

. I want each

to be able to keep track of which grid it is in, but I don't want to create 10,000 copies of the same

for a 100 x 100 grid. Consider the following

made up of

myGrid = cgrid(30, 20)
myGrid = 
  cgrid with properties:
    grid: {30×20 cell}
    M:    30
    N:    20

Now suppose I want each cell to know which grid it is in, so I can write functions for

that extract useful information from the grid (i.e., findNeighbors)

%Snippet of cgrid constructor, modified for clarity
for ii = 1:myGrid.M
    for jj = 1:myGrid.N
       obj.grid{ii, jj} = ccell(ii, jj);       %Creates a ccell object and stores it at the location {ii, jj}                       
       obj.grid{ii, jj}.home = myGrid.grid          %Tells the ccell object where it lives
    end
end

Does this second line of the nested for loop create 600 copies of myGrid? Or does it just point to where myGrid is stored?

Because if I were to take any cell and modify its home, that wouldn't affect my original object of myGrid. It would seem so wasteful for a new object to be created everytime, but I know that somewhere somehow, obj.grid{1,2}.home is NOT the same object as myGrid.grid